27 Jun
2004
27 Jun
'04
11:22 a.m.
Tim Goetze wrote:
[Tim Blechmann]
Three shifts, three copys, three 'or's and an 'and':
copy = value;
value |= copy >> 4;
copy = value;
value |= copy >> 2;
copy = value;
value |= copy >> 1;
value &= 0x01;
On Fri, 25 Jun 2004 17:38:24 -0500
Jan Depner <eviltwin69(a)cableone.net> wrote:
>On Fri, 2004-06-25 at 13:49, Tim Blechmann wrote:
>
>
>>>I have a denormal fix without a branch but you probably don't want
>>>to see it ;-)
>>> It's pretty simple, just OR the bits of the exponent together
>>> which gives either
>>>0 (denormal) or 1, typecast that to float, and then multiply the
>>>original float by that (0.0 or 1.0). Voila, no branch, but it is
>>>messy looking ;-)
>>>
>>>
indeed sounds more like a fun proposal; nonetheless i'm wondering how
many cycles 'ORing the exponent bits together' would take. with an
8-bit exponent and no assumption about its value made, 8 binary
'shift', 7 'or' and 1 'and' statement if i'm not badly
mistaken. and
if i'm not, a branch will probably hurt less.